linux-kernel - [PATCH 1/2] riscv: perf: add guest vs host distinction

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Message-Id: <8e2d2f60fc30d64b6c69b38184a1b640c7b30003.1721271251.git.zhouquan@iscas.ac.cn>
Date: Thu, 18 Jul 2024 19:23:41 +0800
From: zhouquan@...as.ac.cn
To: linux-kernel@...r.kernel.org,
	linux-riscv@...ts.infradead.org,
	kvm@...r.kernel.org,
	kvm-riscv@...ts.infradead.org,
	linux-perf-users@...r.kernel.org
Cc: anup@...infault.org,
	atishp@...shpatra.org,
	paul.walmsley@...ive.com,
	palmer@...belt.com,
	aou@...s.berkeley.edu,
	mark.rutland@....com,
	alexander.shishkin@...ux.intel.com,
	jolsa@...nel.org,
	Quan Zhou <zhouquan@...as.ac.cn>
Subject: [PATCH 1/2] riscv: perf: add guest vs host distinction

From: Quan Zhou <zhouquan@...as.ac.cn>

Introduce basic guest support in perf, enabling it to distinguish
between PMU interrupts in the host or guest, and collect
fundamental information.

Signed-off-by: Quan Zhou <zhouquan@...as.ac.cn>
---
 arch/riscv/include/asm/perf_event.h |  7 ++++++
 arch/riscv/kernel/perf_callchain.c  | 38 +++++++++++++++++++++++++++++
 2 files changed, 45 insertions(+)

diff --git a/arch/riscv/include/asm/perf_event.h b/arch/riscv/include/asm/perf_event.h
index 665bbc9b2f84..5866d028aee5 100644
--- a/arch/riscv/include/asm/perf_event.h
+++ b/arch/riscv/include/asm/perf_event.h
@@ -8,13 +8,20 @@
 #ifndef _ASM_RISCV_PERF_EVENT_H
 #define _ASM_RISCV_PERF_EVENT_H
 
+#ifdef CONFIG_PERF_EVENTS
 #include <linux/perf_event.h>
 #define perf_arch_bpf_user_pt_regs(regs) (struct user_regs_struct *)regs
 
+extern unsigned long perf_instruction_pointer(struct pt_regs *regs);
+extern unsigned long perf_misc_flags(struct pt_regs *regs);
+#define perf_misc_flags(regs) perf_misc_flags(regs)
+
 #define perf_arch_fetch_caller_regs(regs, __ip) { \
 	(regs)->epc = (__ip); \
 	(regs)->s0 = (unsigned long) __builtin_frame_address(0); \
 	(regs)->sp = current_stack_pointer; \
 	(regs)->status = SR_PP; \
 }
+#endif
+
 #endif /* _ASM_RISCV_PERF_EVENT_H */
diff --git a/arch/riscv/kernel/perf_callchain.c b/arch/riscv/kernel/perf_callchain.c
index 3348a61de7d9..c673dc6d9bd2 100644
--- a/arch/riscv/kernel/perf_callchain.c
+++ b/arch/riscv/kernel/perf_callchain.c
@@ -58,6 +58,11 @@ void perf_callchain_user(struct perf_callchain_entry_ctx *entry,
 {
 	unsigned long fp = 0;
 
+	if (perf_guest_state()) {
+		/* TODO: We don't support guest os callchain now */
+		return;
+	}
+
 	fp = regs->s0;
 	perf_callchain_store(entry, regs->epc);
 
@@ -74,5 +79,38 @@ static bool fill_callchain(void *entry, unsigned long pc)
 void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,
 			   struct pt_regs *regs)
 {
+	if (perf_guest_state()) {
+		/* TODO: We don't support guest os callchain now */
+		return;
+	}
+
 	walk_stackframe(NULL, regs, fill_callchain, entry);
 }
+
+unsigned long perf_instruction_pointer(struct pt_regs *regs)
+{
+	if (perf_guest_state())
+		return perf_guest_get_ip();
+
+	return instruction_pointer(regs);
+}
+
+unsigned long perf_misc_flags(struct pt_regs *regs)
+{
+	unsigned int guest_state = perf_guest_state();
+	int misc = 0;
+
+	if (guest_state) {
+		if (guest_state & PERF_GUEST_USER)
+			misc |= PERF_RECORD_MISC_GUEST_USER;
+		else
+			misc |= PERF_RECORD_MISC_GUEST_KERNEL;
+	} else {
+		if (user_mode(regs))
+			misc |= PERF_RECORD_MISC_USER;
+		else
+			misc |= PERF_RECORD_MISC_KERNEL;
+	}
+
+	return misc;
+}
-- 
2.34.1